This invention relates to novel chemical formulations useful for simultaneous cleaning and disinfecting surfaces, especially porous surfaces, such as acoustic ceiling tiles in hospitals and other medical and dental facilities, etc., where at least a virtual 100% kill rate of bacteria and fungi is desired. More particularly, the present invention relates to potentiated disinfectant cleaning solutions comprising as active working ingredients a quaternary ammonium compound, a compatible surfactant other than a quaternary ammonium compound, such as a non-ionic or amphoteric surface active agent, and a solution of hydrogen peroxide. The active ingredients are present in minimal proportional ranges sufficient to achieve a virtual 100 percent kill of the microbes, e.g., bacteria and fungi present.
Furthermore, the invention relates to processes of disinfecting contaminated surfaces/substrates with the foregoing anti-microbial cleaning solutions wherein virtually 100% of bacteria and fungi are destroyed, resulting in the restoration and extension of the useful life of the treated surfaces/substrates.
Disinfection of building interiors and other surfaces is a major concern in hospitals and other health care facilities where the presence of unwanted bacteria may be detrimental to the health of patients and workers. Health care facilities are not alone in their concern for elimination of harmful bacteria and fungi. Surfaces harboring undesirable microorganisms can pose a health threat in schools, office buildings and homes. For that reason, it is highly desirable to disinfect all surfaces in such facilities to remove as many harmful organisms as possible.
A common building surface of particular concern is ceiling tiles. Because of their porosity, ceiling tiles are particularly susceptible to harboring harmful bacteria and other microorganisms, and they are especially difficult to clean. In many instances, cleaning and disinfecting the tiles involves removing the tiles and exposing them to time consuming treatments with bactericidal agents. Even after such treatment significant amounts of bacteria and fungi can remain in the tiles and replicate.
Cleaning compositions exist which can achieve high kill rates of some harmful microorganisms. However, these compositions tend to have relatively high concentrations of toxic ingredients. Safe application of these compositions often requires special handling procedures and precautions. These can include use of protective equipment, such as safety goggles, gloves, coveralls, face masks, and the like. In many cases, additional ventilation of the space being disinfected is essential during and after application of these compositions.
Hydrogen peroxide (H2O2) has been proposed as a bactericide and has been used for many years as a topical antiseptic, especially as a 3% aqueous solution. Addition of ferric or cupric ions, potassium dichromate, cobaltous sulfate, or manganous sulfate is known to enhance the bactericidal action of H2O2.
However, H2O2 suffers from the disadvantage that by itself it is relatively inefficient and is not a potent fungicide. Further, H2O2 especially at higher concentrations is irritating to the skin, eyes, and mucous membranes. Health and safety hazards associated with the use of solutions containing H2O2 increase as the concentration of H2O2 in the solutions increases. It is therefore desirable that disinfecting solutions contain the lowest possible concentrations of H2O2.
Processes and compositions for the disinfection of aqueous media employing hydrogen peroxide are disclosed in U.S. Pat. No. 4,311,598 to Verachtert. The disinfectant comprises a combination of hydrogen peroxide, a soluble copper salt, such as copper sulphate and an autoxisable reducing agent such as ascorbic acid or sodium sulphite. While these compositions appear to be relatively effective in killing bacteria in some aqueous solutions, they are not efficacious fungicides. Nor has their efficacy on surfaces been demonstrated.
Quaternary ammonium compounds, usually tetrasubstituted ammonium salts, have been reported for use as bacteristats, bactericides, and algaecides. Those used as bacteristats and bactericides have required relatively high levels to be effective or have required prolonged contact times.
Examples of references describing the use of quaternary ammonium compounds include U.S. Pat. No. 5,373,025 to Gay which discloses a sanitizer for swimming pools, spas and hot tubs comprising a quaternary ammonium compound and a copper ion source.
Examples of publications disclosing sanitizers combining peroxides with quaternary ammonium compounds include U.S. Pat. No. 5,348,556 to Minns et al. This patent discloses an aqueous composition which cleans and sanitizes carpets, and the like. In general, the compositions contain peroxide in concentrations of about 3% to about 30%, in combination with a volatile ammoniated substance, including tetra butyl ammonium hydroxide, in an amount of about 0.1% to 5%. However, the Minns et al patent does not disclose a fungicide, nor are the compositions disclosed as providing at least a virtual 100% kill rate of bacteria.
U.S. Pat. No. 4,397,757 to Bright et al discloses bleaching and detergent compositions containing hydrogen peroxide and quaternary ammonium activators. While the compositions of the Bright et al patent are disclosed to be effective as whiteners and cleaners, such compositions are not intended to provide high kill rates of bacteria and fungi.
Other patents of interest employing quaternary ammonium compounds are U.S. Pat. Nos. 4,941,989 and 5,320,805 both to Kramer et al. Each of the Kramer patents discloses a variety of compositions, all characterized as prepared from alkaline water soluble xe2x80x9cper saltsxe2x80x9d, preferably from 10 to 90% by weight sodium percarbonate (2Na2CO3.3H2O2); from a fraction of a percent to about 30% by weight of a positively charged phase transfer agent, preferably a quaternary ammonium salt, and a surfactant within a range of about 0.25 to 20% by weight.
According to the Kramer et al patents, the alkaline per salt is dissolved in an aqueous solution of the positively charged quaternary ammonium phase transfer agent to extract a proton from the per salt. According to the express teachings of Kramer et al, in order for the reaction to occur the aqueous medium is required to have a rather high pH of at least 9.5. This high pH is readily attained because per salts, such as sodium percarbonate also yield alkaline sodium carbonate when in water. Such aqueous compositions will typically have pHs in the range of 10 to 11, or more.
While such solutions, according to the Kramer patents, yield hydroperoxide ions, HO2xe2x88x92, to become associated with the positively charged quarternary ammonium ion, it was found that any residual molecular hydrogen peroxide which might otherwise remain in the alkaline solution rapidly breaks down as observed by the prompt release of oxygen bubbles.
Accordingly, the instability of hydrogen peroxide when present in alkaline media severally limits shelf-life and the ability to premix antimicrobial solutions with per salts, like sodium percarbonate (Kramer at al), and be able to store and ship product, and maintain high antimicrobial activity.
As previously pointed out, the patents of Kramer et al disclose various types of compositions prepared with per salts, etc., including creams, bulk powders, tablets, soaps and also solutions. While sodium percarbonate has a listed solubility in water of about 120 gm/L at 20xc2x0 C. the preparation of true solutions, i.e., liquid having a single phase, according to the protocols of the Kramer et al patents by dissolving the granular/solid sodium percarbonate salt in the liquid components were found not to yield true solutions, i.e. liquid with a single phase. Instead, the liquid yields two distinct phases possibly resulting from incompatibilities with other active ingredients in solution, such as the quaternary ammonium compound or surfactant. Hence, these inventors found in attempting to replicate the working examples in accordance with the disclosures of the Kramer et al patents relating to the preparation of solutions with sodium percarbonate, an alkaline pH of at least 10 to 11 resulted in the evolution of oxygen gas, demonstrating the lack of stability and shelf-life, and rapid dissipation of important antimicrobial activity through premature evolution of oxygen bubbles. Furthermore, the liquid compositions of Kramer et al resulted in multi-phase compositions, rather than true single phase solutions when prepared according to the protocols of the working examples.
Accordingly, a need remains for dual action anti-bacterial and anti-fungal solutions which can be readily prepared as true solutions and which are storage stable retaining substantially all their anti-microbial activity even after prolonged periods of storage, and are capable of achieving at least a virtual 100% kill rate for both bacteria and fungi while requiring very low concentrations of potentially corrosive, toxic and other active ingredients. Such disinfectant cleaning solutions should be effective in the restoration of treated surfaces/substrates as to extend their useful lives and avoid the need for more costly replacements.
For purposes of this invention, the terms and expressions below appearing in the specification and claims are intended to have the following meanings:
xe2x80x9cDisinfectantxe2x80x9d refers to any antimicrobial agent which destroys or irreversibly inactivates infectious or other undesirable bacteria, pathogenic fungi on surfaces or inanimate objects.
xe2x80x9cSurfactantxe2x80x9d (surface-active-agent) is generally intended to refer to a substance which when dissolved in water or other aqueous solution reduces the surface or interfacial tension between it and another substance or material. However, for purposes of this invention, the termxe2x80x94surfactantxe2x80x94as appearing in the specification and claims is intended to specifically include only nonionic surfactants, amphoteric surfactants and cationic surfactants other than quaternary ammonium compounds and salts thereof. Surfactants for purposes of this invention do not include negatively charged anionic type surface active agents or other compounds which are incompatible in solution with the disinfecting quaternary ammonium compound component of the potentiated disinfectant cleaning solutions of this invention. In this connection, amphoteric surfactants is intended to include those surface active agents which exhibit cationic properties when in solutions of this invention.
xe2x80x9cVirtual 100% killxe2x80x9d refers to an effective kill of essentially all target organisms existing in a sample, material or substrate to be disinfected and cleaned. This expression is hereby distinguished from the expression xe2x80x9cactual 100% killxe2x80x9d, which is taken to mean a kill of precisely 100% of target organisms. Hence, the expressionxe2x80x94virtual 100% killxe2x80x94means the destruction of slightly less than 100% of the target microbes, i.e., between 96% and 100%.
xe2x80x9cStorage stablexe2x80x9d as appearing in the specification and claims is intended to mean the disinfectant cleaning solutions have good shelf life, remain as solutions and retain the substantial part of their original antimicrobial properties after preparation of the solutions and during extended periods of storage in sealed polymeric containers under ambient temperature conditions.
xe2x80x9cWorking solutionxe2x80x9d as appearing in the claims and specification is intended to mean the prepared solution in ready-to-use format and concentration for applying to a surface for disinfection and cleaning.
In accordance with the invention a principal object is to provide for storage stable potentiated disinfectant cleaning compositions in the form of aqueous solutions. xe2x80x9cSolutionsxe2x80x9d as appearing in the specification and claims is intended to mean a single phase liquid. This excludes multiphase systems or mixtures, such as dispersions of solid particles suspended in a liquid phase, or precipitated solids which separate out of a liquid phase, or mixtures of immiscible liquids, such as emulsions containing separate phases or layers.
The active ingredients of the aqueous working solutions comprise a disinfectant quaternary ammonium compound or salt thereof; a surfactant as previously defined and hydrogen peroxide introduced into the working solution as a solution of hydrogen peroxide. Use of alkaline per salts, such as sodium percarbonate should be avoided because their highly alkaline pH facilitates the decomposition of hydrogen peroxide in solution shortening shelf life, dissipates antimicrobial activity, and for other reasons discussed supra.
The above active ingredients are present in minimal proportional ranges sufficient to achieve at least a virtual 100 percent kill of bacteria and fungi present. Unexpectedly, it was found the combined effect of the foregoing active ingredients together in the same composition effectively enhances both the fungicidal and bactericidal activity beyond the mere additive effects of the individual ingredients used alone or in sub-combinations. Advantageously, the potentiated activity of the disinfectant cleaning solutions of the invention allows for a significant reduction in the proportional ranges of active ingredients otherwise required in such disinfectant compositions. The very low concentration of active ingredients in the working solutions of the invention minimizes the risks of chemical contamination to the environment and hazards of toxicity to personnel applying the compositions, importantly without incurring trade-offs in cleaning and disinfecting performance.
The storage stable aqueous solutions of the invention also have a pH which maintains the shelf-life stability of the working solutions, and in particular, maintains the stability of the hydrogen peroxide, so oxygen is not readily released from solution. The preferred pH for maintaining shelf life stability is approximately a neutral pH of about 7, however, the pH may be somewhat acidic, i.e., in the range of 6 to 7. Likewise, the solutions may also be mildly alkaline, generally in the range of 7 to 7.5, but preferably not above 8. Thus, the pH is generally in the range of about 6 to 8, but more preferably, in the range of about 6.5 to about 7.5.
The quaternary ammonium compounds can be tetrasubstituted ammonium salts, such as a halide salt, e.g., chloride, bromide. However, practically any quaternary ammonium compound possessing some antimicrobial activity, and particularly antibacterial, antifungal and even some antiviral activity, and which is soluble and stable in aqueous solutions with the other active ingredients is suitable.
As previously stated, the surfactant component is intended to include most non-ionic, amphoteric and cationic types. The cationic type can include surfactants other than quaternary ammonium compounds and which are suitable for use in an aqueous system. Surprisingly, the inventors discovered the surfactant ingredient contributes to the potentiated disinfecting action of the compositions, but in addition, imparts detergency properties to the compositions by aiding in dispersing of unwanted foreign matter, such as soil particulates, grease, etc., from the substrate being cleaned.
The hydrogen peroxide ingredient is selected from solutions of hydrogen peroxide, usually from concentrated solutions, like 30%, 40%, or more by weight.
As previously stated, it is an object of the invention to provide for storage stable, potentiated disinfectant cleaning solutions. Working solutions comprise minimal concentrations of the above ingredients to achieve at least a virtual 100% kill of microorganisms. More specifically, the working solutions contain quaternary ammonium compound in an amount ranging from about 0.05% to about 5.0%; surfactant or detergent in an amount from about 0.05% to about 3.5%, and hydrogen peroxide solution in an amount sufficient to provide a working strength solution from about 0.05% to about 10%. Unless stated otherwise, the concentrations of ingredients are based on percent-by-weight.
It is yet a further object of the invention to provide disinfectant cleaning solutions having potentiated bactericidal and fungicidal properties, wherein the working strength solution comprises at least 0.05% by weight hydrogen peroxide prepared from a solution of hydrogen peroxide; as little as about 500 ppm of a dialkyl dimethyl ammonium chloride, N-alkyl dimethyl benzyl ammonium chloride, and from about 0.05% percent to about 3.0% percent of a detergent composition comprising a non-ionic surfactant. The dialkyl dimethyl ammonium chloride is preferably didecyl dimethyl ammonium chloride.
It is still a further object of the invention to provide methods for simultaneously disinfecting and cleaning a surface or substrate so it is free or virtually free of bacteria and fungi, and cleaned of unwanted foreign matter. The method comprises the steps of:
(i) providing a storage stable working disinfectant and cleaning solution comprising a quaternary ammonium compound in an amount ranging from about 0.05% to about 5.0%; surfactant or detergent in an amount from about 0.05% to about 3.5%, and hydrogen peroxide solution in an amount sufficient to provide a working solution with about 0.05 and about 10% of the hydrogen peroxide, and the balance water;
(ii) contacting a surface with a sterilizing amount of the disinfectant cleaning solution of step(i) to provide a surface which is free or virtually free of bacteria and fungi, i.e., at least a virtual 100% kill of bacteria and fungi, and other unwanted foreign matter, such as soil particulates.
The method may be utilized in cleaning, disinfecting and restoring the original appearance to a wide variety of porous and non-porous substrates, particularly surfaces such as brick; cinder block; including wood, plastic and aluminum type siding; fiberglass; concrete and ceiling tiles of various types, to name but a few. The disinfectant cleaning solutions are especially noteworthy in their ability to penetrate, especially porous surfaces, and thereby effectively sterilize the entire substrate, especially in the case of wood based siding products, and acoustical ceiling tiles.
In accordance with the present invention, disinfectant cleaning solutions have been discovered which effectively achieve at least a virtual 100% disinfection and cleaning of surfaces while minimizing the required concentrations of potentially hazardous or toxic ingredients. Table 1 below provides a representative list of bacteria and fungi against which the formulations of the invention were tested for efficacy. As can be seen from the kill rates shown for each organism the formulations of the invention have achieved at least a virtual 100% kill of practically all bacteria and fungi tested, and in many instances achieved an actual 100% kill.
The water clear potentiated disinfectant cleaning formulations are prepared from a solution of hydrogen peroxide in a sufficient amount to provide a hydrogen peroxide concentration from about 0.05% by weight; a surfactant in an amount from about 0.05%; a quaternary ammonium compound such as didecyl dimethyl ammonium chloride, N-alkyl (C12) dimethyl benzyl ammonium chloride, etc., in an amount from about 0.05% and the balance water.
The hydrogen peroxide component of the solution is the oxidant, and is derived from a solutions of hydrogen peroxide, 30 to 40 percent aqueous solutions, for example.
The surfactant may include most commercially available compounds from the classes of non-ionic and amphoteric types, and also includes cationic type surfactants other than quaternary ammonium compounds. Non-ionic types are especially preferred. One particularly suitable non-ionic surfactant, an alkyl phenol ethoxylate is available from the Buffalo Soap Company under product name 201C, and comprises nonyl phenol ethoxylate as the principal ingredient. Other useful non-ionic surfactants include the ethylene oxide/propylene oxide copolymers, and more specifically the ethylene diamine reacted block copolymers available from BASF under the trademarks Tetronic and Pluronic. Other nonionic types include the ethoxylated fatty alcohols containing from 11 to 15 carbon atoms and from 3 to 40 moles of ethylene oxide available from Union Carbide under the trademark Tergitol, and so on. Examples of amphoteric surfactants which are useful as detergents are the imidazolinium derivatives prepared from 2-alkyl-1-(2-hydroxyethyl)-2-imidazolines and sodium chloracetate. This class of surfactants is commercially available from Rhone-Poulenc under such trademarks as Miranol. Also included in this group of amphoteric surfactants are the betaines or sultaines available from Lonza, Inc., under the trademark Lonzaine.
Useful, cationic surfactants other than quaternary ammonium compounds are the polyoxyethylated cationic surfactants. Also included are the amines consisting of aliphatic and mono-, di- and polyamines derived from fatty and rosin acids. They include mainly primary, secondary and tertiary monoamines with C18 alkyl and alkenyl chains. They are commercially available as acetates, oleates, and so on. Other useful cationic surfactants other than quaternary ammonium compounds include the oxygen-containing amines. This group includes amine oxides, ethoxylated alkylamines, 1-(2-hydroxyethyl)-2-imidazolines, and alkoxylates of ethylenediamine.
Most any quaternary ammonium compound, and especially those known to possess some biocidal activity may be used in the formulations of the invention. In one particularly preferred embodiment a tetrasubstituted ammonium salt, such as a quaternary ammonium halide salt can be utilized. The quaternary ammonium halide salt may be selected from the group consisting of a dialkyl-dimethyl ammonium chloride, an alkyl dimethyl benzyl ammonium chloride, an alkyl dimethyl ethyl benzyl ammonium chloride, and mixtures thereof. In one especially preferred embodiment of the invention, the dialkyl dimethyl ammonium chloride salt is didecyl dimethyl ammonium chloride (DDAC) and n-alkyl(C12,C14,C16) dimethyl benzyl ammonium chloride available under the trademark Uniquat(copyright) QAC from Lonza, Inc. Fair Lawn, N.J.
The formulations of the invention may be provided in ready-to-apply, i.e., working solutions diluted with water, or alternatively, may be furnished as concentrates to be later diluted with water at the site to be decontaminated.
The solutions can be applied to a surface, such as ceiling tile by first placing the solution into a reservoir on a spray applicator machine. The suggested temperature of the solution during treatment is typically between about 20xc2x0 C. and about 60xc2x0 C. The solution may then be applied to ceiling tiles, for instance, at a consistent pressure of about 110 psi using a fan nozzle tip having a tip angle of about 25 degrees. The tip is preferably held at a distance of about 8 inches to about 12 inches from the surface to be disinfected.
The recommended water temperature, pressure consistency, angle of the tip and application distance are optimized to properly allow penetration of the surface while preserving important attributes of the ceiling tiles, such as acoustic properties, flame retardant and esthetic features.
As previously mentioned, the solutions and methods of cleaning according to the invention are especially desirable in the renewal of ceiling tiles, such as fiberglass type since they can be disinfected, sanitized and simultaneously cleaned in the same treatment process by the removal of dust and other undesirable particulate matter deposited therein as airborne dirt, as well as grease, bacteria, fungi, and so on, which normally builds up over a period of time due to closed, artificial environments and constant recirculation of air through forced air ventilation heating and cooling systems of buildings. Acoustical ceiling tiles, for example, can function as repositories of potentially toxic bacteria, fungi and even viruses which can contaminate and reinfect the working environment of office buildings, schools, hospitals, etc. Heretofore, the only alternative was to replace literally thousands of ceiling tiles of hospitals which have become soiled and infected with microbes with totally new tiles at very significant cost. Hence, the solutions and methods of the invention are especially advantageous in providing a more economic alternative to the costly option of installing new ceiling tiles.
The following specific examples demonstrate the invention, however, it is to be understood they are for illustrative purposes only and do not purport to be wholly definitive as to conditions and scope.